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March 2005

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Subject:
Re: Paste coverage
From:
"Nowland, Russell Howard (Russell)" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Nowland, Russell Howard (Russell)
Date:
Fri, 25 Mar 2005 10:59:45 -0600
Content-Type:
text/plain
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text/plain (49 lines) 
Jim,

This is not a simple as here is a table and go to it.  IPC 7525 is the Stencil Design Guidelines.  You have to take into account the pitch of the devices, what is in the area, stencil technology, aspect/area ratio, etc...  You can also sit down to do all of the volumetric calculations (paste is roughly 50% solids) and determine the volume you need.  The finer the feature the thinner you have to go in order to maintain the aspect/area ratio or you will not be able to get the paste out of the stencil.  If you want to give more specifics about your concern or the types of components let us know because we all have opinions.  Anymore the standard stencil thickness is typically 6 mils.  If you are doing fun things like Via-in-Pad (VIP) you have to do a lot more planning and compensation.  Happy Easter.

Russell Nowland
Lucent Technologies
Quail Springs Parkway Plaza
14000 Quail Springs Parkway. Suite 300
Oklahoma City, OK 73134
Phone: 405-302-1660
Fax: 405-302-1622
Cell: 405-203-0034
email: [log in to unmask]


-----Original Message-----
From: West, Jim [mailto:[log in to unmask]]
Sent: Friday, March 25, 2005 8:15 AM
To: [log in to unmask]
Subject: [TN] Paste coverage


Hi,

Looking for the standard that discusses the amount of paste coverage
required for each pad.

Jim

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